Evaluating the reliability and validity of the Questionnaire for Lung Transplant Patients.

CONTEXT

The Questionnaire for Lung Transplant Patients was designed for clinical use by the pulmonary transplant team in the routine evaluation of lung transplant recipients. Using the self-administered questionnaire, recipients check symptoms that they have had since their last evaluation and rate their shortness of breath, cough, and activity tolerance.

OBJECTIVE

To determine whether the questionnaire meets reliability and validity standards for empirical measurement.

METHODS

Demographics and disease-severity characteristics were examined in a cross-sectional survey of 37 recipients. Test-retest and intraclass correlation methods were used to estimate stability, and the Cronbach alpha was used to estimate internal consistency. Criterion validity was examined by using The Modified Symptom Frequency/Symptom Distress Scale, Functional Performance Inventory, and visual analog scales for cough and shortness of breath as criterion measures. Construct validity was examined to assess the predicted negative correlation between symptoms and functional performance.

RESULTS

The questionnaire and its subscales were internally consistent (Cronbach alpha = 0.82, 0.76, 0.80, and 0.96), and the questionnaire was stable (r = 0.70) and reliable (intraclass correlations = 0.80 and 0.90). Significant correlations were found between the questionnaire and all criterion measures (r = 0.50-0.93). Significant correlations in the predicted negative direction were found between the respiratory subscale and functional performance (r = -0.51) and between cough (r = -0.51) and shortness of breath (r = -0.68) ratings and functional performance.

CONCLUSIONS

The Questionnaire for Lung Transplant Patients is reliable and valid, and it provides scientifically sound information for clinical and empirical evaluation of symptoms and their effects on activity tolerance after lung transplantation.